1. Field of the Invention
The present invention relates to a reaction force cancel system for improving the stabilization of stages in a movable stage apparatus.
2. Related Background of the Invention
Conventionally, a movable stage apparatus including: a surface plate having a plurality of plate surfaces with different heights from each other, and installed on a base via a vibration-isolating section; and a plurality of stages that move on respective plate surfaces in the surface plate has been in use as an exposure apparatus for semiconductors and liquid crystals, for example. In such a movable stage apparatus, a higher acceleration and deceleration of the stages has been sought for purpose of improving throughput per unit time, for example. However, if the stages are highly accelerated or decelerated, there is a risk that there may be an increase in reaction forces generated in the surface plate upon movements of the stages, and thus the stabilization of the stages may become worse.
Thus, in recent years, a reaction force cancel system has been developed, which is described, for example, in Japanese Patent Application Laid-Open No. 2000-40650. In the reaction force cancel system, an attempt has been made to counterbalance a plurality of reaction forces generated in the surface plate upon movements of a plurality of stages (reticle stage and wafer stage) by applying forces (variable thrusts) for counterbalancing the reaction forces by means of a first application device (force actuator) and a second application device (horizontal force actuator) to the surface plate (mirror cylinder surface plate and reticle stage surface plate), respectively.